We propose to study contextual and genetic influences on adolescent behavioral development. Our analyses will serve to delineate the role that community context plays in the development of individual behavior and psychopathology, and aid our understanding of the way in which contextual variables interact with genetic effects to influence behavioral traits. These general aims will be accomplished by merging contextual data from the 1990 U.S. Census with longitudinal questionnaire and interview data on the behavior, psychopathology and home environment of over 2,400 twins, ages 8-16, residing in the state of Virginia. The collection of the majority of the behavioral data is currently being supported by other funds (MH45268). We will supplement these data with additional child behavior ratings and demographic information obtained from the twins' parents. Initially, aggregate-level contextual variables will be included in univariate genetic analyses of internalizing and externalizing behaviors, major depression and anxiety and conduct disorders. As a result, community context will serve as an index of environmental effects which are common to both twins. More detailed analyses will then be conducted to determine the causal pathways through which context influences behavior. These analyses will include putative mediator variables of context, such as family dysfunction, peer relationships and neighborhood cohesiveness. We will] also consider whether the effect of context on behavior is mediated by age (context x age interactions), and whether genetic influences on behavior are mediated by context (genotype x context interactions). Finally, we will use longitudinal data to explore the causal role life events and context play in the onset of major depression and anxiety and conduct disorders, and the extent to which contextual effects on behavior and psychopathology accumulate over time.